I have a dedicated "rain bike" very simple setup:
* old mountain bike
* single speed
* fenders
* coaster brake
* 2" Serfas city drifters at about 50 psi.
* re-pack all bearing about 2-3x's per year
* Boeshield T9 lube
* thin layer of clear silicone around the headset and seat tube
* lemon pledge on frame helps the water bead off the frame
* plastic bag on Brooks saddle
* clean as needed